24,635 research outputs found
Nonequilibrium transport through a quantum dot coupled to normal and superconducting leads
We study the interacting quantum dot coupled to the normal and
superconducting leads by means of a continuous-time quantum Monte Carlo method
in the Keldysh-Nambu formalism. Deducing the steady current through the quantum
dot under a finite voltage, we examine how the gap magnitude in the
superconducting lead and the interaction strength at the quantum dot affect
transport properties. It is clarified that the Andreev reflection and Kondo
effect lead to nonmonotonic behavior in the nonequilibrium transport at zero
temperature.Comment: 6 pages, 3 figures, conference paper of SCES 201
Systematic Analysis of Frustration Effects in Anisotropic Checkerboard Lattice Hubbard Model
We study the ground state properties of the geometrically frustrated Hubbard
model on the anisotropic checkerboard lattice with nearest-neighbor hopping
and next nearest-neighbor hopping . By using the path-integral
renormalization group method, we study the phase diagram in the parameter space
of the Hubbard interaction and the frustration-control parameter .
Close examinations of the effective hopping, the double occupancy, the momentum
distribution and the spin/charge correlation functions allow us to determine
the phase diagram at zero temperature, where the plaquette-singlet insulator
emerges besides the antiferromagnetic insulator and the paramagnetic metal.
Spin-liquid insulating states without any kind of symmetry breaking cannot be
found in our frustrated model.Comment: 7pages, 5figure
Commutation relations of vertex operators related with the spin representation of
We calculate commutation relations of vertex operators for the spin
representation of by using recursive formulae of R-matrices.
In quantum symmetry approach, we obtain the energy and momentum spectrum of the
quantum spin chain model related with the spin representation from these
commutation relations.Comment: 39 pages amslate
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